Regular expressions with character classes (e.g. [[:digit:]]) are not supported in the default regular expression syntax used by find. You need to specify a different regex type such as posix-extended in order to use them.
Take a look at GNU Find's Regular Expression documentation which shows you all the regex types and what they support.
Well, you may try this '.*[0-9]'
You should have a look on the -regextype argument of find, see manpage:
-regextype type
Changes the regular expression syntax understood by -regex and -iregex
tests which occur later on the command line. Currently-implemented
types are emacs (this is the default), posix-awk, posix-basic,
posix-egrep and posix-extended.
I guess the emacs type doesn't support the [[:digit:]] construct. I tried it with posix-extended and it worked as expected:
find -regextype posix-extended -regex '.*[1234567890]'
find -regextype posix-extended -regex '.*[[:digit:]]'
Note that -regex depends on whole path.
-regex pattern
File name matches regular expression pattern.
This is a match on the whole path, not a search.
You don't actually have to use -regex for what you are doing.
find . -iname "*[0-9]"
Source: Stackoverflow.com